The parts of an exhaust system such as an exhaust manifold, an exhaust pipe, a converter case, and a muffler which are used in the environment of the exhaust system of an automobile are required to be excellent in thermal fatigue resistance, high-temperature fatigue resistance, and oxidation resistance (hereinafter, these are collectively referred to as “heat resistance”). For use applications in which heat resistance is required as described above, nowadays, Cr containing steel to which Nb and Si are added such as JFE429EX (containing 15 mass % Cr-0.9 mass % Si-0.4 mass % Nb) (hereinafter, referred to as Nb—Si added steel) is often used. In particular, it is known that Nb significantly increases heat resistance. When Nb is added, however, not only the material cost increases due to Nb being expensive but also the manufacturing cost of steel increases. Therefore, it is necessary that steel having high heat resistance be developed under the condition that Nb content is controlled to be as small as possible.
In order to solve this problem, Patent Literature 1 discloses a stainless steel sheet whose heat resistance is increased by utilizing the combined addition of Ti, Cu, and B.
Patent Literature 2 discloses a Cu added stainless steel sheet with excellent formability.
Patent Literature 3 discloses a heat-resistant ferritic stainless steel sheet to which Cu, Ti, and Ni are added.